Production of films on plate-glass or other transparent bodies.



reflection and transmission of light,

UNITED STATES PATENT OFFICE: A B

.- JAMES EMERSON REYNOLDS nnnenoncn RUDOLF GRUBBpOEDUBLlN,

. v IRELAND.

PRODUCTION'OF FILMS 0N PLATE-GLASS OR OTHER TRANSPARENT BODIES.

SPECIFICATION forming part of Letters Patent N 0, 722,901, dated March 17, 1903. Application filed September 30, 1901. Serial No. 77.140. (ll'o model.)

To all whom/ it may concern.-

Be it known that we, JAMES EMERSON REY- NOLDS and GEORGE RUDOLF GRUBB, subjects of the King of Great Britain and Ireland, residing at Dublin, Ireland, have invented an Improved Production of Films on Plate- Glass or other Transparent Bodies, of which the following is, a specification.

Layers, or films having lustrous surfaces have been produced on glass and other substances by applying to the surface to be coated a solution containing dissolved lead, with or without other metals in solution, and

a body capable of affording sulfur by gradual decomposition in the liquid; but such layers or films, besides being opaque or translucent, have not been of a uniform and amorphous character, such as is essential to the regular Now this invention has for its object the production on transparent bodies, such as plateglass, glass prisms, lenses, and other shaped pieces of glass, or on other transparentbodies, such as pieces of what are known in optics as pebbles, of practically uniform amorphous transparent films, such as will efliciently serve the twofold purpose-of reflecting and transmitting light. rays, whereby transparent bodies of diderent forms coated with such films can be used for viewing objects .near or at a distance, while at the same time a large amount of light can be reflected from the coated surfaces of such bodies and they can be adapted to serve various useful purposes with great advantage. For this purpose, according to the present invention, the desired filmlis produced by immersing the material tobe coated ina solution of thiourea, (a definite'chemical compound discovered by one of us-namely, the said James Emerson Reynolds-and described in the Journal of the Chemical Society of London, Vol. 7, Second-Series,) to which solution has been added a separate solution in caustic soda of well-washed freshly-precipitated lead tartrate, heating this mixture, adding a further quantity of lead-tartrate solution, lowering the temperature of the mixture under treatment, and allowing the whole to gradually cool, the material under treatment being during the cooling process usually at a slightly-higher temperature than the mix ture, which is advantageous.

In carrying out the invention the two solutions, which we will call for distinction, re-

spectively, Solution A and Solution B, are prepared as follows Solution A is prepared by dissolving thiourea in distilled water, suitable proportions being fifteen 15) grams of thio-urea to one litter of distilled water.

Solution B is prepared by dissolving wellwashed freshly-precipitated lead tartrate in an aqueous solution of caustic soda, suitable proportions being seventy-five (75) grams of the freshly-precipitated well-washed lead tartrate, dissolved in a solution of caustic soda in distilled water containing forty (40) grams of pure caustic soda, (NaOH,) the whole being then made up to one liter.

The precipitate of the requisite amount of ,lead tartrate can conveniently be prepared by adding to the calculated weight of R0- chelle salt in solo tion a sufiicient weight of lead acetateor nitrate also-in solution to completely, precipitate the possible amount of lead tartrate from the salts. Before being dissolved in the caustic-soda solution the freshly precipitated lead tartarate is, While still wet, carefnlly'and repeatedly washed in distilled water by decantation or otherwise, and after the thus-thoroughly-washed lead tartrate has-been dissolved in the causticsoda solution the resulting liquid is kept in an efficiently-closed vessel, such as'a wellstoppered bottle.

In order to produce a transparent film of the character referred to on the material to be coated, a mixture is prepared on the basis of the following proportions-that is to say,

-four,volumes of Solution A are mixed with six volumes of distilled water, and to this 7 mixture there is added of Solutiou B a volume equal to from one-fortieth to one-fiftieth, or thereabout, of the total volume of Solution A. The body to'be coated, which we will assuine to be of glass and which m ust be scrupu-. louslyplean, is immersed in the mixture produced as last above described, and the mixture and the body under treatment within the mixture are gradually raised to and kept at a temperature of, say, Fahrenheit un- IOO ' the water in it to fall from, say,

til the solution assumes a dark sherry color.

the requisite film of lead sulfid in the de-' sired condition. I The water-bath should preferably be of such capacity as to allow the temperature of 120 to 110 Fahrenheit in about fifteen minutes.

The'transparent body should be kept in a state of motion throughout the period during which it is immersed in the solution.

In practice the body whereof a surface or surfaces is or are to be coated is wholly immersed in the liquid, and during the cooling process its temperature remains, as aforesaid, slightly in excess of the temperature of the gradually-cooling liquid. It will be understood that the entire surface of the immersed piece of glass or other From those portions of the surface of the body where the coating is not required it can be readily removed by the application of any suitable solvent-such, for example, as hydrochloric acid. I

What we claim is- 1. The hereinabove -described process of producing a film on a transparent body, said process consisting in immersing the body to be coated in a solution of thio-urea to which has been added a separate solution in caustic alkali of well-washed freshly-precipitated lead tartrate.

2. The hereinabove-described process of producing a film on a transparent body, said process consisting in subjecting the body to be coated to the action of a heated solution of thio-urea to which has been added a separate solution in caustic alkali of well-washed freshly-precipitated lead tartrate.

3. The hereinabovedescribed process of producing a film on a transparent body, said process consisting in immersing the body to be coated in a solution of thio-urea to which hasbeen added a separate solution in caustic alkali of well -washed freshly-precipitated lead tartrate, heating this mixture and adding thereto a further quantity of lead-tartrate solution.

4. The hereinabovedescribed process of producing a film on a transparent body, said process consisting in immersing the body to be coated in a solution of thio-urea to which has been added a separate solution in caustic alkali of well-washed lead tartrate, heating this mixture, adding thereto a further quantity of lead-tartrate so-- lution, and lowering the temperature of said mixture.

5. The hereinabove-described process of producing a film on a transparent body, said process consisting in immersing the body to body becomes coated.

freshly precipitated be coated in a solution of thio-urea to whichhas been added a separate solution in caustic alkali of well -washe'd freshlyprecipitated lead tartrate, heating this mixture, adding thereto a further quantity of lead-tartrate solution, lowering the temperature of the mixture and allowing the whole to cool gradually while keeping the temperature of the body under treatment slightly higher than that of the liquid in which it is immersed.

6. The hereinabove-described process of coating a transparent body, said process consisting in immersing the body in a film-forming liquid consisting of a mixture of a solution prepared by dissolving about fifteen grams of thio-urea in one liter of distilled water and adding distilled water thereto in the proportion of 'six volumes of distilled water to four volumes of the solution, and of a solution prepared by dissolving about seventy- ,five grams of well-washed freshly-precipitated lead tartrate in an aqueous solution of about forty grams of pure caustic soda, and making up to one liter, the second solution being added to the first in the proportion of from one-fortieth to one-fiftieth part of the total volume of the first solution.

7. The hereinabove-described process of forming a film on a transparent body,-said process consisting in immersing the body in a liquid consisting of a mixture of a solution prepared by dissolving about fifteen grams of thio-urea in one liter of distilled water, and adding distilled .water thereto in the proportion of six volumes of distilled water to four volumes of the solution, and of a solution prepared by dissolving about seventy-five grams of well-washed freshly-precipitated lead tar-' trate in an aqueous solution of about forty grams of pure caustic soda,and making up to one liter, the second solution being added to the first in the proportion of from one-fortieth to one-fiftieth part of the total volume of the first solution, gradually raising the temperature of the mixture and of the body under treatment therein to about 140 Fahrenheit, keeping the whole at about the same temperature until the liquid assumes a dark sherry color, adding a further quantity, in the cold, of the second solution, placing the vessel containing the liquid and the transparent body in a bath having a temperature of about 120 Fahrenheit, and allowing the whole to cool to about 110 Fahrenheit.

8. The hereinabove-described process of forming a film on a transparent body, said process consisting in immersing the body in a liquid consisting of a mixture of a solution prepared by dissolving about fifteen grams of thio-urea in one liter of distilled water, and adding distilled water thereto in the proportion of six volumes of distilled water to four volumes of the solution, and of a solution prepared by dissolving about seventy-five grams one liter, the second solution being added to the first in the proportion of from one-fortieth to one-fiftieth part of the total volume of the first solution, gradually raising the temperature of the mixture and of the hodyunder treatment therein to about 140? Fahrenheit, keeping the whole at about the same temperature until the liquid assumes a. dark sherry color, adding gradually a further quantity, in the cold, of thesecond solution, placing the vessel containing the liquid and the transparent body in a bath havinga temperature of about 120 Fahrenheit, and allowing the whole to cool to about 110 Fahrenheit.

9. The hereinabove-described process of producing a film on a transparent body, said process consisting in immersing the body to be coated in a solution of thio-urea to which has been added a separate solution in caustic alkali of well-washed freshly-precipitated lead tartrate, and maintaining said body in'a state of motion during the formation thereon of the film.

Signed at Dublin this 18th day of September, 1901.

JAMES EMERSON REYNOLDS. GEORGE RUDOLFGRUBB. Witnesses:

ROMNEY R. GRUBB, O. W. POOLEY. 

